The translation units were probably a better place back when most of
the codebase was still compiled in C mode, we only had a few C++ TUs,
almost everything needed to be declared as `extern "C"`, and moving
these declarations into the headers would have been really noisy with
all the `#ifdef __cplusplus` / `#endif` required. Nowadays though,
we've greatly reduced that surface area. And given that headers will
include even more headers as part of the upcoming `#include` cleanup,
it makes sense to make the jump now.
Part of P0284, funded by [Anonymous] and Blue Bolt.
I might change this convention again in the future, particularly once
someone wants to fund C89 conformance, but let's stay consistent for
now.
Part of P0264, funded by [Anonymous] and Blue Bolt.
motion_t is also used for certain animations in MAINE.EXE, so not all
instances refer to entities in playfield space. Explicitly specifying
the latter now allows us to gain…
Part of P0149, funded by Blue Bolt, Ember2528, and -Tom-.